The present invention relates to a fitting for a plastic pipe and, more in particular, it relates to a fitting for a plastic pipe comprising a fitting main body and a retaining ring put over the top end of a plastic pipe, which can simply and reliably connect a plastic pipe and easily confirm the state of operation.
As pipelines for supplying hot water and water, and pipelines for heat medium for warming a floor, fluid supplying pipes made of plastics (hereinafter referred to as plastic pipes) have been popularized with a view point, for example, of corrosion resistance, earthquake proofness, sanitation and operability. A fitting used, for example, in a case of connecting a plastic pipe to an equipment is described, for example, in Japanese Industrial Standards JIS B 2354. Such a fitting comprises a fitting main body having at one end an inner core to which the top end of a plastic pipe is inserted, a bite-type ring put over the top end of the plastic pipe and a cap nut for tightening the plastic pipe by way of the bite-type ring.
However, since the existent fitting described above comprising three parts, namely, the fitting main body, the bite-type ring and the cap nut, it is difficult to reduce the manufacturing cost and the administration cost for parts. Further, in the connecting operation, since the cap nut and the bite-type ring have to be mounted successively to the end of the pipe previously and clamped by the cap nut, there arises a problem of complicating the operation. In addition, since the top end of the plastic pipe is covered with the cap nut, there arises in a problem that complete fitting of the plastic pipe as far as a predetermined position at the base end of the inner core of the fitting main body can not be inspected directly.
As a result of the present inventions' earnest studies for (1) reduction of the number of constitutional parts, (2) simple and reliable operation, and (3) easy inspection after the operation, it has been found that by constituting the fitting with two members, that is, a fitting main body and a retaining ring having a specified structural means, such a fitting for a plastic pipe overecomes the foregoing problems. On the basis of the finding, the present invention has been attained.